In order to preserve this scarce resource, guidelines developed by the WHO encourage the rational use of blood transfusion and recommend that transfusion be reserved for children with profound anaemia (Hb ≤4 g/dL) or for those with a Hb between 4 to 6 g/dL who have additional severity critieria in areas where malaria is hyperendemic but suggest a higher transfusion threshold of 7 g/dl in areas of low malaria transmission [21]. The gene discussed is GSTM1; the disease is anemia (phenotype).